Benzyl­ethyl­dimethyl­ammonium bromide

Maciej Hodorowicz; Katarzyna Stadnicka

doi:10.1107/S1600536808002481

. 2008 Feb 15;64(Pt 3):o601. doi: 10.1107/S1600536808002481

Benzylethyldimethylammonium bromide

Maciej Hodorowicz ^a,^*, Katarzyna Stadnicka ^a

PMCID: PMC2960757 PMID: 21201938

Abstract

The crystal structure of the title compound, C₁₁H₁₈N⁺·Br⁻, has been determined as part of an ongoing study of the influence of the alkyl chain length on amphiphilic activity of quaternary ammonium salts. The title salt forms a three-dimensional network of ionic contacts through weak C—H⋯Br hydrogen bonds, with donor–acceptor distances in the range 3.757 (2)–3.959 (2) Å, in which methyl groups serve as donors.

Related literature

For related literature, see: Ogawa & Kuroda (1997 ▶); Hodorowicz et al. (2003 ▶, 2005 ▶); Kwolek et al. (2003 ▶); Allen et al. (1987 ▶).

Experimental

Crystal data

C₁₁H₁₈N⁺·Br⁻
M _r = 244.17
Orthorhombic,
a = 6.7765 (1) Å
b = 12.5827 (2) Å
c = 13.9433 (2) Å
V = 1188.90 (3) Å³
Z = 4
Mo Kα radiation
μ = 3.42 mm⁻¹
T = 293 (2) K
0.20 × 0.19 × 0.17 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (DENZO and SCALEPACK Otwinowski & Minor, 1997 ▶) T _min = 0.548, T _max = 0.594 (expected range = 0.516–0.559)
18366 measured reflections
3874 independent reflections
3483 reflections with I > 2σ(I)
R _int = 0.041

Refinement

R[F ² > 2σ(F ²)] = 0.027
wR(F ²) = 0.065
S = 1.07
3874 reflections
119 parameters
H-atom parameters constrained
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.49 e Å⁻³
Absolute structure: Flack (1983 ▶), with 1627 Friedel pairs
Flack parameter: 0.002 (9)

Data collection: COLLECT (Nonius, 2000 ▶); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO (Otwinowski & Minor, 1997 ▶) and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808002481/cf2179sup1.cif

e-64-0o601-sup1.cif^{(16.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808002481/cf2179Isup2.hkl

e-64-0o601-Isup2.hkl^{(186.1KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg1 is the centroid of the benzene ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4—H4A⋯Br1	0.97	2.81	3.757 (2)	164
C2—H2A⋯Br1ⁱ	0.96	2.96	3.850 (3)	154
C4—H4B⋯Br1ⁱ	0.97	2.96	3.832 (2)	151
C3—H3B⋯Br1ⁱ	0.97	3.08	3.950 (2)	151
C3—H3A⋯Br1ⁱⁱ	0.97	3.19	3.959 (2)	138
C1—H1C⋯Br1ⁱⁱⁱ	0.96	2.99	3.766 (2)	139
C2—H2C⋯Cg1ⁱⁱ	0.96	2.69	3.526	145

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

The authors thank the Joint X-ray Laboratory, Faculty of Chemistry, and SLAFiBS, Jagiellonian University, for making the Nonius KappaCCD diffractometer available.

supplementary crystallographic information

Comment

Quaternary alkylammonium salts are widely used to modify natural clay minerals into hydrophobic organo-clays which exhibit high capability to remove hydrophobic contaminants from aqueous solutions (Ogawa & Kuroda, 1997). From the systematic study of the relation between the crystal structures of chosen homologous benzyldimethylalkylammonium bromides and their cations' ability for sorption on clay minerals (Kwolek et al., 2003; Hodorowicz et al., 2003, 2005), it became obvious that the hydrophobic interactions are responsible for an alkyl-chain bilayer formation when the long-chain (n = 8–12) ammonium cations are adsorbed on montmorillonite (Hodorowicz et al., 2005), whereas a different way of cation packing seems to dominate in the case of short-chain ammonium cations (Kwolek et al., 2003). The crystal structure analysis of benzyldimethylethylammonium bromide was performed to find out the influence of molecular geometry, and the length of the alkyl chain in particular, on the packing properties of the ammonium cations. The structure of the title compound is shown in Fig. 1. The asymmetric unit is composed of a quaternary ammonium cation and a bromide counterion (N⁺···Br^- = 4.439 (2) Å). The bond lengths and angles indicate the typical tetrahedral arragement of the substituents at the N atom. The molecular dimensions are comparable with the values reported in the literature (Allen et al., 1987). Methyl and methylene groups of the quaternary ammonium cation as well as C—H of the benzene ring are involved in weak intermolecular interactions of the C—H···Br^- type (Table 1). There are also relatively strong interactions of the C—H···π type observed between the C2 methyl group and the π system of the benzene ring, which result in cation chains along [100] (Fig. 2). The chains are joined into layers parallel to (010) due to C—H···Br^- interactions (Fig. 3). The interactions are also responsible for packing of the layers along [010], as shown in Fig. 4. Each layer consists of cations inclined to the anionic layer and arranged in a zig—zag 'head-to-tail' system. The thickness of the layer is b/2. The observed architecture of the short-chain ammonium cation layers, best seen in Figs. 3 and 4, could be considered as a model for the organic cation layers intercalated into the montmorillonite structure (Kwolek et al., 2003).

Experimental

The title compound was prepared by dissolving a 1:1 mixture of bromoethane and N,N-dimethylbenzylamine in acetone at 273 K. The solution was slowly heated to room temperature to give colourless single crystals of the title compound. Recrystallization from acetone afforded crystals suitable for X-ray measurements.